Multi-layered optical communication networks have many benefits but many problems as well, such as the presence of physical layer impairments. The multi-layered network problems can be decomposed into four subproblems: deciding the lightpaths of the virtual topology (logical topology design), routing the electronic layer traffic on the resulting virtual topology (traffic routing), routing the lightpaths on the physical topology (lightpath routing), and assigning the wavelengths to lightpaths (wavelength assignment). The first two problems correspond to the MPLS layer and can be referred as the single-layer virtual topology design problem, while the remaining two make up the routing and wavelength assignment (RWA) problem in the WDM layer. For successful communication through the established lightpaths, physical layer impairments should also be considered in the RWA problem, together with wavelength continuity and fiber capacity constraints.
Due to the large number of variables and constraints in both layers, a complete joint solution to these four problems has not proven tractable so far for moderate and large size networks. When they are solved separately, care must be taken to provide a strong integration between the solutions; otherwise, the complete solution may result in having a worse performance. Because of the computational complexity of the joint problem, most approaches focus on the subproblems corresponding to one layer and omit those arising in the other layer, or make simplifying assumptions to relax some of the subproblems.
Many RFCs have been published to address these issues. For example:                RFC2702 defines requirements for Traffic Engineering (TE) over MPLS networks. Specifically, it defines resource class and Affinity constructs to allow for various TE policy implementations.        RFC3630—defines OSPF extensions to advertise resource class information as Administrative Group (AG).        RFC 7308—enhances AG construct to go beyond 32 limit.        RFC 3209—defines RSVP-TE extensions to carry Affinity information in signaling.        RFC 5212—defines MN/MRN requirements.        
One significant problem is that multi-layer networks typically operate as client-server layers. Server-layer connections may be required for client layer to offer services. The aforementioned RFCs cover how Resource Color and Affinity concepts can be applied at a given client or network layer only and not in a multi-layer context. What is needed is an approach that may be used in a multi-layer network to achieve network resource isolation among clients using same server network, such as a VPN in a multi-layered network described herein.
Accordingly, there is a need for systems, apparatus, and methods that improve upon conventional approaches including the improved methods, system and apparatus provided hereby.